During the first ascent of the Matterhorn, a remarkable optical effect comprising three crosses surrounded by a great arch was observed by Edward Whymper, the British mountaineer. The authors review previous published explanations of the apparition. There are no photographs, only a woodcut and sketch, so the size of the apparition is not known, and it is not possible to make a definitive conclusion about what caused it. A fogbow and ice crystal arcs could have produced a circle and crosses in a direction consistent with the apparition. Some simulations are presented; one has a form approximating Whymper's sketch. However, while this simulation used a crystal type that can occur, it required an unusual alignment that would be very rare.
© 2005 Optical Society of America
(010.1290) Atmospheric and oceanic optics : Atmospheric optics
Cedric John Hardwick and Jason C. Knievel, "Speculations on the possible causes of the Whymper apparition," Appl. Opt. 44, 5637-5643 (2005)